3phase 3speed motors

[659stearman]

thread237-313373 I have a 3speed 3phase motor 480 volt with no schematic to go by. My question is, is there a way to read the resistances of the 9 motor leads and know which 9 power leads these go to. It's very confusing. No name plates or diagrams to go by. The power comes from 3 magnetic starters on anotherfloor in in buiding. Any help or suggestion would be greatly appreciated.

 

[waross]

A three speed motor with nine leads may have three independent windings. Check the continuity between the motor leads first.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[LionelHutz]

Is there also a shorting contactor in the control cabinet?

If yes, then you have a 2-speed 1-winding motor and another seperate 3-phase single speed winding. The single winding will be easy to determine but you may need a motor shop to sort out the 2-speed 1-winding part.

If no, then you should have 3 seperate 3-phase windings. This should be easy to determine by continuity.

 

[ScottyUK]

Other possible connection is Dahlander winding plus an independent third winding.

 

[LionelHutz]

Dahlander winding = 2-speed 1-winding

 

[ScottyUK]

Yes Lionel, that gives two speeds with an integer ratio between them, and the third winding gives a further speed.